$Larry has just updated the pod: doc/trunk/design/syn/S03.pod =head1 Changes to existing operators -If one argument is insufficiently dimensioned, Perl "upgrades" it: +If either argument is insufficiently dimensioned, Perl "upgrades" it: (3,8,2,9,3,8) >>-<< 1; # (2,7,1,8,2,7) @@ -354,11 +354,26 @@ [[1, 2], 3] »+« [4, [5, 6]] # [[1,2] »+« 4, 3 »+« [5, 6]] # == [[5, 6], [8, 9]]
+More generally, hyper operators work recursively for any object +matching the C<Each> role even if the object itself doesn't support +the operator in question: + + Bag(3,8,[2,Seq(9,3]],8) >>-<< 1; # Bag(2,7,[1,Seq(8,2)],7) + Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,1,1); # Bag(2,7,[1,Seq(8,2)],7) + Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,2,1); # Bag(2,7,[2,Seq(9,3)],7) That last one puzzles me - by this info: -If one argument is insufficiently dimensioned, Perl "upgrades" it: +If either argument is insufficiently dimensioned, Perl "upgrades" it: (3,8,2,9,3,8) >>-<< 1; # (2,7,1,8,2,7) shouldn't it be (not knowing what to do w/ Bag or Seq): Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,2,1); # Bag(2,7,[0,Seq(8,3)],7) or: Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,2,1); # Bag(2,7,[0,Seq(7,2)],7) (the '2' being 'upgraded to [2,2] or [2,2,2] or [2, Seq(2,2)]) + +In particular, tree node types with C<Each> semantics enable visitation: + + $tree.».foo; # short for $tree.each: { .foo } + +You are not allowed to define your own hyper operators, because they +are supposed to have consistent semantics derivable entirely from +the modified scalar operator. If you're looking for a mathematical +vector product, this isn't where you'll find it. A hyperoperator +is one of the ways that you can promise to the optimizer that your +code is parallelizable. (The tree visitation above is allowed to +have side effects, but it is erroneous for the meaning of those side +effects to depend on the order of visitation.) a Andy Bach, Sys. Mangler Internet: [EMAIL PROTECTED] VOICE: (608) 261-5738 FAX 264-5932 "Truth is eternal, knowledge is changeable. It is disastrous to confuse them." -- Madeleine L'Engle